any of you do stump grinding? a friend is looking into it, and i've also thought about it. i'd get one of the smaller 20 horse units, that loads onto a small trailer, and can get through a yard gate. i know they take a good amount of maintenance, but ive done lots of work on them at the Vermeer dealer i worked at. is there money in this? how much do you charge, i understand it usually goes by so much an inch of diameter. do you leave the chips to fill the hole, or how much do you charge to haul it away? any insight will be appreciated. thanks very much.